Long Term Land Use - Precipitation Feedbacks in the Hai River and Poyang Lake Regions

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On all scales, the components of the hydrological cycle are continuously changing and affect the availability and quality of water as essential pre-requisites for human development and sustainable ecological conditions. Hydrological change can be mainly attributed to climate change due to increased greenhouse gas emissions, land cover conversions, and water resources management due to human development. In all three cases, feedback mechanisms between the atmosphere, the land surface, and the subsurface play a crucial role for correct quantification of past, current and future expected water availability. Dynamic feedbacks between the compartments are primarily due to the water and energy fluxes at and between the land surface/subsurface and the atmosphere that are inextricably intertwined over a large range of space- and time-scales. Up to now, feedback analysis is hampered by the lack of appropriate regional model systems that are truly able to account for the long term, i.e. climatic relevant feedback processes between the compartments for meso-scale catchments (up to several 100,000 km²). While most of climate change or land use change hydrological impact assessments rely on simple one-way coupled applications of regional atmospheric models and distributed hydrological models, the development and application of a fully two way coupled model system would close a central gap in hydrological research. It is therefore the objective of PreFeed to develop such a fully two way coupled, meso-scale regional model system, apply it to the two target regions Hai River and Poyang Lake Region and to investigate long term feedback mechanisms between groundwater-, soil moisture dynamics and precipitation. This fully two way coupled mesoscale atmosphere-terrestrial hydrology model system will be realised by tightly coupling the mesoscale meteorological model WRF/Noah-LSM and the newly developed distributed hydrological model Noah-LSM/HMS. Land surface – precipitation feedback measures will be quantified on multiple temporal and spatial scales. Finally, transient regional simulations using the fully coupled model system for 1960-2050 will be performed for different land use representations and the impact of joint climate change-land sue change will be estimated for the two target regions.